Packages for semiconductor light emitting devices utilizing dispensed encapsulants

ABSTRACT

A submount for mounting an LED chip includes a substrate, a die attach pad configured to receive an LED chip on an upper surface of the substrate, a first meniscus control feature on the substrate surrounding the die attach pad and defining a first encapsulant region of the upper surface of the substrate, and a second meniscus control feature on the substrate surrounding the first encapsulant region and defining a second encapsulant region of the upper surface of the substrate. The first and second meniscus control features may be substantially coplanar with the die attach pad. A packaged LED includes a submount as described above and further includes an LED chip on the die attach pad, a first encapsulant on the substrate within the first encapsulant region, and a second encapsulant on the substrate within the second encapsulant region and covering the first encapsulant.

FIELD OF THE INVENTION

This invention relates to semiconductor light emitting devices andmethods of fabricating semiconductor light emitting devices, and moreparticularly to packaging and packaging methods for semiconductor lightemitting devices.

BACKGROUND

Light emitting diodes and laser diodes are well known solid stateelectronic devices capable of generating light upon application of asufficient voltage. Light emitting diodes and laser diodes may begenerally referred to as light emitting devices (“LEDs”). Light emittingdevices generally include a p-n junction formed in an epitaxial layergrown on a substrate such as sapphire, silicon, silicon carbide, galliumarsenide and the like. The wavelength distribution of the lightgenerated by the LED generally depends on the material from which thep-n junction is fabricated and the structure of the thin epitaxiallayers that make up the active region of the device.

Typically, an LED includes a substrate, an n-type epitaxial regionformed on the substrate and a p-type epitaxial region formed on then-type epitaxial region (or vice-versa). In order to facilitate theapplication of a voltage to the device, an anode ohmic contact is formedon a p-type region of the device (typically, an exposed p-type epitaxiallayer) and a cathode ohmic contact is formed on an n-type region of thedevice (such as the substrate or an exposed n-type epitaxial layer).

In order to use an LED in a circuit, it is known to enclose an LED in apackage to provide environmental and/or mechanical protection, colorselection, focusing and the like. An LED package also includes means,such as electrical leads or traces, for electrically connecting the LEDchip to an external circuit. In a typical package 10 illustrated in FIG.1A, an LED 12 is mounted on a reflective cup 13 by means of a solderbond or conductive epoxy. One or more wirebonds connect the ohmiccontacts of the LED 12 to leads 15A, 15B, which may be attached to orintegral with the reflective cup 13. The reflective cup may be filledwith an encapsulant material 16 containing a wavelength conversionmaterial such as a phosphor. Light emitted by the LED at a firstwavelength may be absorbed by the phosphor, which may responsively emitlight at a second wavelength. The entire assembly is then encapsulatedin a clear protective resin 14, which may be molded in the shape of alens to collimate the light emitted from the LED chip 12. While thereflective cup may direct light in an upward direction, optical lossesmay occur when the light is reflected (i.e. some light may be absorbedby the reflector cup instead of being reflected).

In another conventional package 20 illustrated in FIG. 1B, a pluralityof LED chips 22 are mounted onto a printed circuit board (PCB) carrier23. One or more wirebond connections are made between ohmic contacts onthe LEDs 22 and electrical traces 25A, 25B on the PCB 23. Each mountedLED 22 is then covered with a drop of clear resin 24, which may provideenvironmental and mechanical protection to the chips while also actingas a lens. The individual packaged LEDs 22 may then be separated bysawing the PCB carrier 23 into small squares, each of which contains oneor more LED chips 22.

SUMMARY

Embodiments of the invention provide a submount for mounting an LEDincluding a substrate having an upper surface, a die attach padconfigured to receive an LED chip on the upper surface of the substrate.A first meniscus control feature on the substrate surrounds the dieattach pad defines a first encapsulant region of the upper surface ofthe substrate. A second meniscus control feature on the substratesurrounds the first encapsulant region and defines a second encapsulantregion of the upper surface of the substrate. In some embodiments, thefirst and second meniscus control features are substantially coplanarwith the die attach pad.

In other embodiments, the substrate is a printed circuit board (PCB).The die attach pad and the first and second meniscus control featuresmay be formed as metal traces on the substrate. In some embodiments, themeniscus control features may include a material different than the dieattach pad. For example, the meniscus control features may include apolymer such as a solder mask material and/or polyimide. In someembodiments, the die attach pad and the first and second meniscuscontrol features include the same material. Further, the first and/orsecond meniscus control features may include a plated copper or othermetal film formed directly on the substrate. The first and/or secondmeniscus control feature may include a corner of a patterned feature onthe substrate. Further, the die attach pad may include a metal stack onthe metal trace.

In further embodiments of the invention, a wirebond pad on the substrateis disposed within the second encapsulant region. The wirebond pad maybe disposed within the first encapsulant region. The substrate mayinclude a lower surface opposite the upper surface of the substrate, andthe submount may further include all electrode on the lower surface ofthe substrate. A conductive via may extend through the substrate fromthe electrode to the die attach pad. Further, a conductive via mayextend through the substrate from the electrode to the wirebond pad.

In other embodiments, an electrode may be on the upper surface of thesubstrate. The electrode may be formed of the same material as the firstand second meniscus control features. Further, a conductive via mayextend through the substrate from the lower electrode to the electrodeon the upper surface of the substrate.

In yet further embodiments, the submount may also include a thirdmeniscus control feature disposed within the first encapsulant regionand surrounding the die attach pad. The third meniscus control featuremay define a third encapsulant region within the first encapsulantregion. The first meniscus control feature and the third meniscuscontrol feature may together define a region in the first encapsulantregion surrounding the third encapsulant region. The region of the firstencapsulant region defined by the first meniscus control feature and thethird meniscus control feature may be ring-shaped.

In other embodiments, the submount may include at least one surfacefeature on the substrate between the first meniscus control feature andthe second meniscus control feature. The submount may include a one ormore surface features on the substrate between the first meniscuscontrol feature and the second meniscus control feature, wherein a pathextending in a radial direction from the first meniscus control featureto the second meniscus control feature is interrupted by at least onesurface feature. The surface feature(s) may be continuous ordiscontinuous and may be formed of the same material as the first andsecond meniscus control features. For example, the surface feature(s)may include a metal film such as a plated copper film. In someembodiments, the surface feature(s) may include a material differentthan the die attach pad. For example, the surface feature(s) may includea polymer such as a solder mask material and/or polyimide.

In yet other embodiments, a submount for mounting an LED includes asubstrate having an upper surface and a conductive pattern on the uppersurface of the substrate. The conductive pattern includes a portionconfigured to receive an LED chip. A first meniscus control feature onthe substrate surrounds the submount and defines a first encapsulantregion of the upper surface of the substrate. A second meniscus controlfeature on the substrate surrounds the first encapsulant region anddefines a second encapsulant region of the upper surface of thesubstrate.

The conductive pattern may include a conductive trace directly on thesubstrate, and may further include a wirebond pad disposed within thesecond encapsulant region. The wirebond pad may be disposed within thefirst encapsulant region. The conductive pattern may additionallyinclude an electrode disposed outside the second encapsulant region.

In some embodiments, a packaged LED includes a submount as describedabove and further includes an LED chip on the die attach pad, a firstencapsulant on the substrate within the first encapsulant region, and asecond encapsulant on the substrate within the second encapsulant regionand covering the first encapsulant.

A packaged LED according to some embodiments of the invention mayfurther include a wirebond connection between the LED chip and thewirebond pad. In addition, a packaged LED may further include anelectrostatic discharge (ESD) protection chip on the die attach pad. Thefirst and/or second encapsulant may include a silicone gel and/or anepoxy resin. In addition, the first and/or encapsulant may include awavelength conversion material such as, for example, a phosphor and/or ananocrystal.

In some embodiments a packaged LED includes a submount as describedabove, and further includes an LED chip on the die attach pad. A firstencapsulant is provided on the substrate within the region of the firstencapsulant region defined by the first meniscus control feature and thesecond meniscus control feature. A second encapsulant is provided on thesubstrate within the third encapsulant region. A third encapsulant isprovided on the substrate within the second encapsulant region coveringthe first encapsulant and the second encapsulant.

In yet other embodiments, methods of forming LED submounts and packagedLEDs are provided including depositing a metal layer on a substrate andpatterning the metal layer to form a die attach pad, a first meniscuscontrol feature that surrounds the die attach pad and defines a firstencapsulant region of the upper surface of the substrate, and a secondmeniscus control feature that surrounds the first encapsulant region anddefines a second encapsulant region of the upper surface of thesubstrate.

Some methods of forming a packaged LED include depositing a metal layeron a substrate and patterning the metal layer to form a die attach pad,a first meniscus control feature, and a second meniscus control feature.The first meniscus control feature may surround the die attach pad anddefine a first encapsulant region of the upper surface of the substrate.The second meniscus control feature may surround the first encapsulantregion and define a second encapsulant region of the upper surface ofthe substrate.

Other methods according to the invention further include mounting an LEDchip on the die attach pad on the substrate. A first encapsulantmaterial may be dispensed onto the substrate and the mounted LED chipwithin the first encapsulant region, and the first encapsulant materialmay be cured. After curing the first encapsulant material, a secondencapsulant material may be dispensed onto the substrate within thesecond encapsulant region, and the second encapsulant material may becured. A quantity of encapsulant material may be pre-dispensed adjacentthe LED chip prior to dispensing the first encapsulant material. In someembodiments, a sufficient quantity of the first encapsulant material maybe dispensed to substantially cover the LED chip.

In some embodiments, patterning the metal layer includes patterning themetal layer to form a wirebond pad within the second encapsulant region.The method may further include forming a wirebond connection between theLED chip and the wirebond pad.

In some embodiments, the first encapsulant material includes awavelength conversion material, such as a phosphor and/or a nanocrystal.Patterning the metal layer may further include forming at least onesurface feature between the first and second meniscus control features.The surface features may help the encapsulant material adhere to thesurface of the substrate and/or cling to the meniscus control features.

Methods of forming a packaged LED according to further embodiments ofthe invention include depositing a metal layer on a substrate andpatterning the metal layer to form a die attach pad, a first meniscuscontrol feature, a second meniscus control feature and a third meniscuscontrol feature. The first meniscus control feature may surround the dieattach pad and define a first encapsulant region of the upper surface ofthe substrate. The second meniscus control feature may surround thefirst encapsulant region and define a second encapsulant region of theupper surface of the substrate. The third meniscus control feature maybe formed within the first encapsulant region and may surround the dieattach pad to thereby define a third encapsulant region within the firstencapsulant region. The first meniscus control feature and the thirdmeniscus control feature may together define a region in the firstencapsulant region surrounding the third encapsulant region. The firstencapsulant material may be dispensed in a shape corresponding to ashape of the region surrounding the third encapsulant region. Forexample, in some embodiments of the invention, the shape of the regionsurrounding the third encapsulant region is annular, and the firstencapsulant material may be dispensed by moving a dispensing needle in acircular motion.

In other embodiments, an LED chip is mounted on the die attach pad and afirst encapsulant material is dispensed within the region in the firstencapsulant region defined by the first meniscus control feature and thethird meniscus control feature. The first encapsulant material may thenbe cured and a second encapsulant material may be dispensed onto thesubstrate within the third encapsulant region. The second encapsulantmaterial may then be cured. A third encapsulant material may bedispensed within the second encapsulant region, and the thirdencapsulant material may be cured. The dispensed first encapsulantmaterial may define a cavity around the LED chip, and dispensing thesecond encapsulant material may include dispensing the secondencapsulant material into the cavity around the LED chip after curingthe first encapsulant material. The first encapsulant material, thesecond encapsulant material and/or the third encapsulant material mayinclude a wavelength conversion material.

In further methods, a meniscus extension feature may be formed outsidethe second encapsulant region. The meniscus extension feature maysurround the second encapsulant region and define a encapsulantextension area of the upper surface of the substrate. A fourthencapsulant material may be dispensed in the encapsulant extension areaafter curing the second encapsulant material and curing the fourthencapsulant material. The encapsulant extension area may have aperipheral shape that is different from a peripheral shape of the secondencapsulant region. For example, the encapsulant extension area may havea peripheral shape that is oval, circular, rectangular and/or generallysquare. In some embodiments, the meniscus extension features may includea material different than the die attach pad. For example, the meniscuscontrol features may include a polymer such as a solder mask materialand/or polyimide.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are cross-sectional side views illustrating conventionallight emitting device packages;

FIG. 2A is a cross-sectional view illustrating a light emitting devicesubmount according to some embodiments of the invention;

FIG. 2B is a top view illustrating the light emitting device submount ofFIG. 2A;

FIG. 2C is a cross sectional view illustrating a light emitting devicepackage according to some embodiments of the invention utilizing thesubmount of FIG. 2A;

FIG. 3A is a cross-sectional view illustrating a light emitting devicesubmount according to further embodiments of the invention;

FIG. 3B is a top view illustrating the light emitting device submount ofFIG. 3A;

FIG. 3C is a cross sectional view illustrating methods of forming alight emitting device package according to some embodiments of theinvention utilizing the submount of FIG. 3A;

FIG. 3D is a cross sectional view illustrating a light emitting devicepackage according to some embodiments of the invention utilizing thesubmount of FIG. 3A;

FIGS. 4A-4D are cross sectional views illustrating methods of forming alight emitting device package according to some embodiments of theinvention;

FIG. 5 is a top view illustrating a light emitting device submountaccording to further embodiments of the invention;

FIG. 6A is a top view illustrating a light emitting device submountaccording to further embodiments of the invention;

FIG. 6B is a cross sectional view illustrating a light emitting devicepackage according to some embodiments of the invention utilizing thesubmount of FIG. 6A;

FIG. 6C is a perspective view of a light emitting device packageaccording to some embodiments of the invention utilizing the submount ofFIG. 6A;

FIG. 7 is a top view illustrating a light emitting device submountaccording to further embodiments of the invention;

FIG. 8 is a schematic illustration of a system for dispensing anencapsulant material for use in packaging a light emitting deviceaccording to some embodiments of the invention; and

FIGS. 9-11 are flowcharts illustrating methods according to someembodiments of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The present invention now will be described more fully with reference tothe accompanying drawings, in which embodiments of the invention areshown. This invention may, however, be embodied in many different formsand should not be construed as limited to the embodiments set forthherein. Rather, these embodiments are provided so that this disclosurewill be thorough and complete, and will fully convey the scope of theinvention to those skilled in the art. In the drawings, the size andrelative sizes of layers and regions may be exaggerated for clarity.Like numbers refer to like elements throughout.

It will be understood that when an element such as a layer, region orsubstrate is referred to as being “on” another element, it can bedirectly on the other element or intervening elements may also bepresent. It will be understood that if part of an element, such as asurface, is referred to as “inner,” it is farther from the outside ofthe device than other parts of the element. Furthermore, relative termsSuch as “beneath” or “overlies” may be used herein to describe arelationship of one layer or region to another layer or region relativeto a substrate or base layer as illustrated in the figures. It will beunderstood that these terms are intended to encompass differentorientations of the device in addition to the orientation depicted inthe figures. Finally, the term “directly” means that there are nointervening elements. As used herein, the term “and/or” includes any andall combinations of one or more of the associated listed items. As usedherein, the common abbreviation “e.g.”, which derives from the Latinphrase “exempli gratia,” may be used to introduce or specify a generalexample or examples of a previously mentioned item, and is not intendedto be limiting of such item. If used herein, the common abbreviation“i.e.”, which derives from the Latin phrase “id est,” may be used tospecify a particular item from a more general recitation.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, components, regions, layersand/or sections, these elements, components, regions, layers and/orsections should not be limited by these terms. These terms are only usedto distinguish one element, component, region, layer or section fromanother region, layer or section. Thus, a first element, component,region, layer or section discussed below could be termed a secondelement, component, region, layer or section without departing from theteachings of the present invention.

Embodiments of the invention are described herein with reference tocross-sectional, perspective, and/or plan view illustrations that areschematic illustrations of idealized embodiments of the invention. Assuch, variations from the shapes of the illustrations as a result, forexample, of manufacturing techniques and/or tolerances, are to beexpected. Thus, embodiments of the invention should not be construed aslimited to the particular shapes of regions illustrated herein but areto include deviations in shapes that result, for example, frommanufacturing. For example, a region illustrated or described as arectangle will, typically, have rounded or curved features due to normalmanufacturing tolerances. Thus, the regions illustrated in the figuresare schematic in nature and their shapes are not intended to illustratethe precise shape of a region of a device and are not intended to limitthe scope of the invention.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andthis specification and will not be interpreted in an idealized or overlyformal sense unless expressly so defined herein.

Various embodiments of the present invention for packaging asemiconductor light emitting device will be described herein. As usedherein, the term semiconductor light emitting device may include a lightemitting diode, laser diode and/or other semiconductor device whichincludes one or more semiconductor layers, which may include silicon,silicon carbide, gallium nitride and/or other semiconductor materials, asubstrate which may include sapphire, silicon, silicon carbide and/orother microelectronic substrates, and one or more contact layers whichmay include metal and/or other conductive layers. In some embodiments,ultraviolet, blue and/or green light emitting diodes may be provided.Red and/or amber LEDs may also be provided. The design and fabricationof semiconductor light emitting devices are well known to those havingskill in the art and need not be described in detail herein.

For example, the semiconductor light emitting device may be galliumnitride-based LEDs or lasers fabricated on a silicon carbide substratesuch as those devices manufactured and sold by Cree, Inc. of Durham,N.C. The present invention may be suitable for use with LEDs and/orlasers as described in U.S. Pat. Nos. 6,201,262; 6,187,606; 6,120,600;5,912,477; 5,739,554; 5,631,190; 5,604,135; 5,523,589; 5,416,342;5,393,993; 5,338,944; 5,210,051; 5,027,168; 5,027,168; 4,966,862 and/or4,918,497, the disclosures of which are incorporated herein by referenceas if set forth fully herein. Other suitable LEDs and/or lasers aredescribed in published U.S. Patent Publication No. US 2003/0006418 A1entitled Group III Nitride Based Light Emitting Diode Structures With aQuantum Well and Superlattice, Group III Nitride Based Quantum WellStructures and Group III Nitride Based Superlattice Structures,published Jan. 9, 2003, as well as published U.S. Patent Publication No.US 2002/0123164 A1 entitled Light Emitting Diodes IncludingModifications for Light Extraction and Manufacturing Methods Therefor.Furthermore, phosphor coated LEDs, such as those described in U.S.Patent Publication No. 2004/0056260 A1, entitled Phosphor-Coated LightEmitting Diodes Including Tapered Sidewalls and Fabrication MethodsTherefor, the disclosure of which is incorporated by reference herein asif set forth fully, may also be suitable for use in embodiments of thepresent invention. The LEDs and/or lasers may be configured to operatesuch that light emission occurs through the substrate. In suchembodiments, the substrate may be patterned so as to enhance lightoutput of the devices as is described, for example, in the above-citedU.S. Patent Publication No. US 2002/0123164 A1.

Referring to the embodiments of FIGS. 2A-2C, a submount 100 for mountingan LED chip 114 is illustrated. A submount 100 includes a substrate 110having an upper surface 110A and a lower surface 110B. The substrate 110may include a printed circuit board (PCB), an aluminum block, analumina, aluminum nitride or silicon wafer, or any other suitablesubstrate material, such as T-Clad thermal clad insulated substratematerial, available from The Bergquist Company of Chanhassen, Minn.

As illustrated in FIGS. 2A-2C, a plurality of patterned metal featuresare formed on the upper surface 110A of the substrate 110. The patternedmetal features may include, for example, a die attach pad 112, a wirebond pad 120, a first meniscus control feature 116, a second meniscuscontrol feature 118, and/or electrodes 124. The conductive features onthe top surface 110A of substrate 110 may be formed, for example, usinga plating process. A plating process may be used to plate a thin orthick metallic film on a substrate. In a typical plating process, atitanium adhesion layer and a copper seed are sequentially sputteredonto a substrate. Then, approximately 75 microns of copper are platedonto the copper seed. Thus, a plating process may be utilized to form ametal film having a characteristic structure. A deposited metal film maybe patterned using standard lithographic processes to produce metalfilms on the substrate having desired patters. Alternatively, theadhesion layer and seed may be sputtered using, for example, a metalmask to form a desired pattern. A plating process may also be used toform conductive metal vias through a substrate.

In some embodiments of the invention, the first and second meniscuscontrol features 116, 118 maybe formed of a material different from thedie attach pad 112 and/or the wirebond pad 120. For example, themeniscus control features 116, 118, 210 may comprise a polymer such as asolder mask material including for example polyimide. In particular, apolymer such as polyimide may provide a suitable material for use as ameniscus control feature since polyimide may have a high surface energy,which may provide better meniscus control properties.

The conductive vias may provide electrical contact between featuresformed on opposite sides of a substrate. Accordingly, respectiveconductive features formed on the upper surface of substrate 110 may beformed of the same material. For example, the conductive features mayinclude copper deposited using a plating process. However, in someembodiments, some features may include additional metals. For example,the die attach pad 112 may be plated and/or coated with additionalmetals and/or other materials to make the die attach pad 112 moresuitable for mounting an LED chip 114. For example, the die attach pad112 may be plated with additional layers such as, for example,additional adhesive, bonding, reflector and/or barrier layers (notshown).

As illustrated in the embodiments of FIG. 2B, the die attach pad 112 maybe generally centrally located on the upper surface 110A of thesubstrate 110. The die attach pad 112 may be generally circular inshape, or may have any other desired shape. As further shown in FIG. 2B,the first meniscus control feature 116 formed on the substrate 110surrounds the die attach pad 112 and defines a first encapsulant region115 on the upper surface 110A of the substrate 110 within the peripheryof the first meniscus control feature 116. The second meniscus controlfeature 118 surrounds the first encapsulant region 115 and defines asecond encapsulant region 125 on the upper surface 110A of the substrate110 within the periphery of the second meniscus control feature 118. Asillustrated in FIG. 2B, the second encapsulant region 125 may encloseand encompass the first encapsulant region 115.

The wirebond pad 120 may be formed on the upper surface 110A ofsubstrate 110 within the first encapsulant region 115 and/or within thesecond encapsulant region 125. One or more of the electrodes 124 mayalso be formed on the upper surface 110A of the substrate 110. Inaddition, one or more lower electrodes 126 may be formed on a lowersurface 110B of the substrate 110 as shown in FIG. 2A.

One or more conductive vias 122 may connect one or more of the lowerelectrodes 126A, 126B to various features on the upper surface 110A ofthe substrate 110. For example, one of the conductive vias 122 mayelectrically connect the electrodes 124A, 124B with respective lowerelectrodes 126A, 126B. Likewise, one of the conductive vias 122 mayelectrically connect the wire bond pad 120 with the lower electrode126A, and/or one of the conductive vias 122 may electrically connect thedie attach pad 112 with the lower electrode 126B.

As illustrated in the embodiments of FIG. 2C, an LED chip 114 mounted onthe die attach pad 112 may be covered with an encapsulant material 130.The encapsulant material 130 may be dispensed onto the upper surface110A of the substrate 110 using, for example, an automated dispensesystem, as described more fully below. The encapsulant material 130 mayinclude a liquid silicone, an epoxy resin, and/or another suitableoptical encapsulant material. The encapsulant material 130 may include awavelength conversion material, such as a phosphor and/or a nanocrystal,therein to convert a wavelength of light emitted by the LED chip 114 toa second wavelength.

As illustrated in FIG. 2C, the first encapsulant material 130 isdispensed within the first encapsulant region 115 defined by the firstmeniscus control feature 116. When the first encapsulant material 130 isdispensed within the first encapsulant region 115, it may form a liquidmeniscus (i.e. a curved bubble or dome) over the LED chip 114. Surfacetension in the liquid encapsulant material 130 may cause it to cling tothe first meniscus control feature 116. For example, the liquidencapsulant material 130 may cling to a corner 116 a of the firstmeniscus control feature 116 and/or a surface of the first meniscuscontrol feature 116. For example, as illustrated in FIG. 2C, theencapsulant material 130 may cling to a corner 116 a of the meniscuscontrol feature 116 that is farthest from the center of the dome of theencapsulant material 130. The dispensed first encapsulant material 130may be cured, for example, by heating at an appropriate temperature foran appropriate time, to cause the first encapsulant material to hardenover the LED chip 114. It will be appreciated that a cure step mayinclude a full and/or partial curing of an encapsulant material. A fullcure may cause the liquid encapsulant material to harden completely,while a partial cure may cause the liquid encapsulant to only partiallyharden. For example, it may be desirable to partially cure a dispensedliquid encapsulant sufficient to permit a subsequent dispense and/orother process steps to be performed. A full cure may be performed aftersome or all subsequent dispenses have been performed. Alternatively, itmay be desirable to perform a full cure after each dispense step.

As further illustrated in FIG. 2C, a wirebond connection 128 may beformed between the LED chip 114 and the wire bond pad 120. The wirebondconnection 128 may be made before dispense of the first encapsulantmaterial 130, so that when it is cured, the first encapsulant material130 may harden around the wirebond connection 128.

After the first encapsulant material 130 has been cured, a secondencapsulant material 140 may be dispensed within the second encapsulantregion 125 of the upper surface 110A of the substrate 110, i.e. over thecured first encapsulant material 130. The second encapsulant material140 may form a meniscus dome over the second encapsulant region 125. Aswith the first encapsulant material 130, the second encapsulant material140 may cling to a corner 118 a or a surface of the second meniscuscontrol feature 118 due, for example, to surface tension in theencapsulant material 140. The second encapsulant material 140 mayinclude a clear silicone gel, an epoxy resin, and/or any other opticallyclear encapsulant material. The dispensed second encapsulant material140 may be cured, for example, by heating the encapsulant material to asuitable temperature for a suitable time period, to cause the secondencapsulant material 140 to harden. The second encapsulant material 140may accordingly form an optically transparent lens over the cured firstencapsulant material 130 and the LED chip 114.

An LED chip 114 packaged in accordance with some embodiments of theinvention may approximate an ideal point source of light. Thus, thedesign of secondary optics (not shown) for the packaged LED may besimplified. In addition, light output of the packaged LED may beimproved as optical losses associated with mounting an LED chip inside areflector cup may be avoided when an LED chip 114 is packaged inaccordance with some embodiments of the invention.

Referring to FIGS. 3A-3D further embodiments according to the inventionare illustrated. As illustrated in FIG. 3A, a submount 200 for mountingan LED chip 114 includes a substrate 110 having an upper surface 110Aand a lower surface 110B. A plurality of metal features are formed onthe upper surface 110A of the substrate 110, for example, by a platingprocess. For example, as with the embodiment illustrated in FIGS. 2A-2C,the submount 200 may include a die attach pad 112, a wire bond pad 120,a first meniscus control feature 116 defining a first encapsulant region115, and a second meniscus control feature 118 defining a secondencapsulant region 125. In addition, embodiments of the invention mayfurther include a third meniscus control feature 210 formed within thefirst encapsulant region 115 surrounding the die attach pad 112 anddefining a third encapsulant region 215. In addition, the first meniscuscontrol feature 116 and the third meniscus control feature 210 define aregion 225 within the first encapsulant region 115 surrounding the thirdencapsulant region 215. As noted above, the meniscus control features116, 118, 210 may include a material different from the die attach pad112 and the wirebond pad 120. For example, the meniscus control features116, 118, 210 may include a polymer such as polyimide.

As illustrated in FIG. 3B, the first meniscus control feature 116,second meniscus control feature 118 and third meniscus control feature210 may be generally circular in shape. Accordingly, the region 225defined between the first meniscus control feature 116 and the thirdmeniscus control feature 210 may be generally annular or ring-shaped. Anencapsulant material may be deposited in an annular region 225 in forexample, a circular pattern, by moving a dispensing needle in a circularmotion as discussed in more detail below. In this manner, the desiredpattern may be “drawn” onto the substrate with the needle.

Other shapes may be possible for the first, second and third meniscuscontrol features 116, 118, 210. For example, the meniscus controlfeatures could be generally oval and/or rectangular in shape. In someembodiments, the meniscus control features may be continuous featuresformed on the upper surface 110A of the substrate 110. If the meniscuscontrol features are not continuous features, encapsulant materialdispensed within regions defined by the meniscus control features may bemore likely to fail to be confined within a desired region.

As illustrated in FIG. 3A, a first encapsulant material 230 may bedispensed within the region 225 defined by the first meniscus controlfeature 116 and the third meniscus control feature 210. As illustratedin FIG. 3A, the first encapsulant material 230 may cling to a corner 116a of the first meniscus control feature 116 and a corner 210 a of thethird meniscus control feature 210 that are distant from the center ofregion 225. That is, when it is dispensed, the encapsulant material 230may flow outward until it reaches an outer corner of the respectivefirst and third meniscus control features 116, 210 where it may be heldin place, for example, by surface tension. The dispensed firstencapsulant material 230 may be cured, for example, by heating theencapsulant material for a suitable period of time at a suitabletemperature, by allowing the dispensed encapsulant to sit for a suitableperiod of time at room temperature, by exposure to UV light, and/or withthe aid of a catalyst. The cured first encapsulant material 230 maythereby form a hardened ring surrounding the third encapsulant region215 including the die attach pad 112 and the LED chip 114 mountedthereon. In some embodiments, the first encapsulant material 230 maydefine a cavity 220 surrounding the LED chip 114. The height of thefirst encapsulant material 230 may be greater than, equal to, or lessthan the height of the mounted LED chip 114 on the die attach pad 112.

As illustrated in FIG. 3C, a second encapsulant material 240 may bedispensed into the cavity 220 defined by the first encapsulant material230. In some embodiments, the second encapsulant material 240 mayinclude a wavelength conversion material, such as a phosphor and/ornanocrystal. The dispensed second encapsulant material 240 may be curedin the manner described above. Next, as illustrated in FIG. 3D, a thirdencapsulant material 250 may be dispensed within the second encapsulantregion 125 (i.e. over the first encapsulant material 230 and the secondencapsulant material 240). The third encapsulant material 250 may form adomed meniscus lens above the LED chip 114, the first encapsulantmaterial 230 and the second encapsulant material 240. The dispensedthird encapsulant material 250 may be cured as described above.

Further embodiments of the invention are illustrated in FIGS. 4A-4C. Inthe embodiments of FIGS. 4A-4D, a single patterned surface feature 308provides the first meniscus control feature 116 at a first corner 308 aof the feature 308 and the third meniscus control feature 210 at theopposite corner 308 b of the feature 308. The first corner of thefeature 308 may correspond to an outer circumference of a generally ringshaped feature. The second corner of the feature 308 may correspond toan inner circumference of the feature 308. The first encapsulantmaterial 230 may be dispensed by dispensing an encapsulant materialabove the feature 308. The encapsulant material 230 may flow outward onthe feature 308 and cling to the inner and outer peripheral edges of thefeature 308 (i.e., the first meniscus control feature 116 and the thirdmeniscus control feature 210, respectively). As shown in FIG. 4B, thesecond encapsulant material 240 may be dispensed within the cavity 220defined by first encapsulant material 230. The third encapsulantmaterial 250 may be dispensed within the second encapsulant region 125to form a dome-shaped meniscus lens above the LED chip 114.

As illustrated in FIG. 5, some embodiments according to the inventionmay include one or more surface features 310 formed on the upper surface110A of substrate 110 between the first meniscus control feature 116 andthe second meniscus control feature 118. The surface features 310 mayinclude a plurality of patterned features arranged to overlap oneanother such that an arbitrary path 325 extending in a radial directionfrom the first meniscus control feature 116 to the second meniscuscontrol feature 118 is interrupted by at least one surface feature 310.The surface features 310 may perform a number of functions. First, thesurface features 310 may provide a patterned feature on the uppersurface 110A of the substrate 110 to which an encapsulant materialdispensed over the surface may grip, which may provide a better, moremechanically robust connection between the encapsulant material and theupper surface 110A of the substrate 110. In addition, the surfacefeatures 310 may slow the flow of liquid encapsulant material across thesurface of the region in which the surface features 310 are formed sothat, for example, the liquid encapsulant material may be more likely tocling to a meniscus control feature as desired. For example, when anencapsulant material is dispensed within the second encapsulant region125, if the material flows too quickly within region 125, it may flowover the meniscus control feature 118 and out of the second encapsulantregion 125. However, when the flow of the second encapsulant material140 is limited by the surface features 310, the encapsulant material maymore reliably cling to the second meniscus control feature 118. Thesurface features 310 are illustrated between the first meniscus controlfeature 116 and the second meniscus control feature 118 in FIG. 5.However, it will be understood by those skilled in the art that thesurface features 310 could be formed in any region of the upper surface110A on which encapsulant material is to be dispensed Moreover, it willbe understood that while the surface features 310 are illustrated asbeing discontinuous, the surface features 310 could be continuousprovided they are small enough or formed with an appropriate shapeand/or thickness such that encapsulant material will not undesirablycling to an edge or surface of the surface feature 310.

Referring now to FIGS. 6A-6C, further embodiments according to theinvention are illustrated. As shown in FIG. 6A, one or more meniscusextension features 300A, 300B may be formed on the upper surface 110A ofsubstrate 110 outside the second meniscus control feature 118. Asillustrated in FIG. 6A, the meniscus extension features 300A, 300B mayhave peripheral geometries different from the peripheral geometry of thesecond meniscus control feature 118. In the embodiment illustrated inFIG. 6A, the second meniscus control feature 118 has a generallycircular shape, while the meniscus extension features 300A, 300B havegenerally elliptical shapes with sequentially increasing axis lengthsand eccentricities (i.e. increasing ratios of major axis length to minoraxis length). After deposition and curing of the second encapsulantmaterial 140, the shape of the lens formed by the second encapsulantmaterial 140 may be modified by dispensing additional encapsulantmaterial within the regions defined by the encapsulant extensionfeatures 300A and 300B. Thus, the ultimate shape of the lens coveringthe LED chip 114 may be determined by the shape of the encapsulantextension features 300A, 300B, as well as the number of dispense/curesteps employed. Multiple encapsulant extension features 300A, 300B maybe employed to gradually increase the size and/or change the shape ofthe lens while limiting the amount of encapsulant material that needs tobe dispensed in any given dispense/cure cycle. Although two encapsulantextension features 300A, 300B are illustrated in FIGS. 6A-6C, it will beappreciated that more or less encapsulant extension features may beprovided. The surface features 310 and/or the meniscus extensionfeatures 300A, 300B may include patterned metal films that may be formedconcurrently with the formation of the die attach pad 112. In someembodiments of the invention, the surface features 310 and/or themeniscus extension features 300A, 300B may include a different materialsuch as a polymer such as polyimide.

As illustrated in FIG. 6B, after deposition and curing of the secondencapsulant material 140, a quantity of encapsulant material 330A may bedispensed within the region 315A bounded by the encapsulant extensionfeature 300A. The encapsulant material 330A may be cured to form ahardened dome 332A having a different peripheral shape than the domeformed by the second encapsulant material 140. If desired, a secondquantity of the encapsulant material 330B may be dispensed within theregion 315B defined by the encapsulant extension feature 300B. Thedispensed encapsulant material 330B may be cured to form a hardened lens332B over the LED chip 114 having a different peripheral shape thansecond encapsulant material 140 or the dome 332A. This process may berepeated as desired until a desired shape of meniscus lens is formedabove the LED chip 114.

FIG. 6C is a perspective view of a resulting LED package 350. includinga substrate 110 on which is formed a hardened dome lens 332A.

As shown in FIG. 7, the encapsulant extension regions may have shapesother than circular or oval. In particular, the encapsulant extensionfeatures 300A, 300B may have peripheral shapes that are generally squareand/or rectangular. Other shapes are possible and may be used to producedifferent shaped lenses as desired.

The ability to deliver small volumes of fluids accurately may beimportant in the manufacture of packaged LEDs according to theinvention. A variety of different fabrication operations in thesemiconductor industry utilize sub-microliter control of fluiddispensing. Such uses may utilize accurate, repeatable and rapiddispensing of precise amounts of fluids. Inaccurate dispensing mayadversely impact the yield of a fabrication process.

As discussed above, after the light-emitting device 114 is mounted onthe substrate 110, a microliter quantity of an encapsulant material,such as liquid silicone gel, is dispensed into one or more encapsulantregions. In dispensing the encapsulant material, a bead of the materialis typically formed on a dispensing needle and then contacted tosurfaces of the substrate 110 and/or the light-emitting device 114. Whenthe needle is withdrawn, the surface tension between the encapsulantmaterial and surfaces on the substrate 110 and gravity may cause theencapsulant material to tear-off from the dispensing needle and remainon the substrate 110. In some embodiments, the encapsulant material maybe dispensed in a desired pattern, for example, a circular pattern, bymoving the needle in a circular motion after contacting the bead to thesurface of the substrate. In this manner, the desired pattern may be“drawn” onto the substrate with the needle.

A system 400 for dispensing an encapsulant material for use in packaginga light emitting device according to some embodiments of the inventionis illustrated in FIG. 8. The system 400 includes a frame 402, which maybe attached to an articulated arm (not shown) configured to controllablymove the frame 402 in the X, Y, and Z dimensions. A needle mount member404 is mounted on the frame 402, and an encapsulant supply line 406 iscoupled to the needle mount member 404 for supplying a quantity ofencapsulant material to a hollow dispensing needle 408 mounted on theneedle mount member 404. A bead of encapsulant 410 may be formed at thetip of the dispensing needle 408. As discussed above, the bead ofencapsulant 410 may be dispensed onto the substrate 110 and/or the LEDchip 114 by contacting the bead 410 to a surface of the substrate 110and/or the LED chip 114. Moreover, the shape of the dispensedencapsulant may be controlled by moving the frame 402 in the X and Ydimensions as the encapsulant is being dispensed. For example, theencapsulant may be effectively dispensed into an annular region bymoving the frame in a circular pattern after contacting the bead 410 toa surface of the substrate 110 within the annular region.

The viscosity and/or other properties of the material used for adispense may be selected such that, for example, wetting occurs withoutbubble formation. In further embodiments of the present invention,coatings may be applied to surfaces contacted by the dispensed materialto speed/retard the wetting rate. For example, using certain knowncleaning procedures that leave microscopic residue, selected surfacesmay be treated and, thus, used to engineer the dynamics of the wettingaction.

Due to the surface properties of the substrate 110, the LED chip 114 andof the encapsulant material 410, the dispensed encapsulant material mayflow in a manner that could cause bubbles to form therein. Inparticular, the encapsulant material may move or “wick” more rapidlyaround the sidewalls of the LED chip 114 faster than over the top of theLED chip 114. As a result, a bubble could be trapped on a side of theLED 114 opposite from the side where the encapsulant material isdispensed when the side-flowing encapsulant material meets, and thenencapsulant material flows over the top of the LED chip 114.Accordingly, when encapsulant material is dispensed into an encapsulantregion including the LED chip 114, such as, for example, the encapsulantregion 115 illustrated in FIG. 2B, the encapsulant may be pre-dispensedin a first dispense portion adjacent the LED chip 114 selected tosubstantially cover the LED chip 114 and a second dispense portionselected to fill the encapsulant region 115. The quantity of the firstportion of dispensed encapsulant material may be selected to reduce orprevent the risk of forming bubbles around the LED chip 114. As such, asused herein, reference to “substantially” covering the LED chip 114refers to covering enough of the structure of the LED chip 114 so thatsuch a bubble will not generally result when the remaining portion ofthe encapsulant material dispensed. After the initially dispensedportion of encapsulant material is allowed to settle, the second portionof the encapsulant material may be dispensed into the encapsulantregion.

Methods of forming LED submounts and packaged LEDs according to someembodiments of the invention are further illustrated in FIGS. 9-11. Themethods illustrated in FIGS. 9-11 are described with reference to theembodiments illustrated in FIGS. 2A-8 above. As illustrated in FIG. 9,some methods 500 of forming an LED submount according to someembodiments of the invention includes depositing a metal layer on asubstrate 110 (block 510); and patterning the metal layer to form a dieattach pad 112, a first meniscus control feature 116 surrounding the dieattach pad 112 and defining a first encapsulant region 115 of the uppersurface of the substrate 110, and a second meniscus control feature 118surrounding the first encapsulant region 115 and defining a secondencapsulant region 125 of the upper surface of the substrate 110 (block520).

Methods of forming a packaged LED according to some embodiments of theinvention are illustrated in FIG. 10. As illustrated therein, methods600 according to some embodiments of the invention may includedepositing a metal layer on a substrate 110 (block 610) and patterningthe metal layer to form a die attach pad 112, a first meniscus controlfeature 116, and a second meniscus control feature 118 (block 620). Thefirst meniscus control feature surrounds the die attach pad 112 anddefines a first encapsulant region 115 of the upper surface of thesubstrate 110, and the second meniscus control feature 118 surrounds thefirst encapsulant region 115 and defines a second encapsulant region 125of the upper surface of the substrate 110.

The method 600 further includes mounting an LED chip 114 on the dieattach pad 112 on the substrate 110 (block 630). A first encapsulantmaterial 130 is then dispensed onto the substrate 110 and the LED chip114 within the first encapsulant region 115 (block 640), and the firstencapsulant material 130 is cured (block 650).

After curing the first encapsulant material, a second encapsulantmaterial 140 is dispensed onto the substrate 110 within the secondencapsulant region 125 (block 660), and the second encapsulant material140 is cured (block 670).

In some embodiments, patterning the metal layer includes patterning themetal layer to form a wirebond pad 120 within the second encapsulantregion 125. In some embodiments, the method further includes forming awirebond connection between the LED chip 114 and the wirebond pad 120.

As discussed above, some embodiments of the invention includepre-dispensing a quantity of encapsulant material adjacent the LED chip114 prior to dispensing the first encapsulant material 130. Moreover, asufficient quantity of the first encapsulant material 130 may bepre-dispensed to substantially cover the LED chip 114. In someembodiments, the first encapsulant material 130 includes a wavelengthconversion material such as a phosphor or a nanocrystal.

Patterning the metal layer may further include forming at least onesurface feature 300 between the first and second meniscus controlfeatures 118. As discussed above, the surface features 300 may help theencapsulant material adhere to the surface 110A of the substrate 110and/or cling to the meniscus control features 116, 118.

Referring now to FIG. 11, further methods 700 of forming a packaged LEDaccording to some embodiments of the invention are illustrated thatinclude depositing a metal layer on a substrate 110 (block 710). Themetal layer is patterned to form a die attach pad 112, a first meniscuscontrol feature 116, a second meniscus control feature 118 and a thirdmeniscus control feature 210 (block 720). As discussed above, the firstmeniscus control feature 116 may surround the die attach pad 112 anddefine a first encapsulant region 115 of the upper surface of thesubstrate 110. The second meniscus control feature 118 may surround thefirst encapsulant region 115 and define a second encapsulant region 125of the upper surface of the substrate 110. The third meniscus controlfeature 210 is formed within the first encapsulant region 115 and maysurround the die attach pad 112 to thereby define a third encapsulantregion 215 within the first encapsulant region 115. The first meniscuscontrol feature 116 and the third meniscus control feature 210 define aregion 225 in the first encapsulant region 115 surrounding the thirdencapsulant region 215. It will be understood that for a feature to“surround” a region, the feature need not be continuously formed aroundthe region. Although the figures illustrate continuous features, it maybe possible for a meniscus control feature to include gaps or voidstherein which do not affect the meniscus control function of thefeature.

The methods 700 may further include mounting an LED chip 114 on the dieattach pad 112 (block 730) and dispensing a first encapsulant material230 within the region 225 in the first encapsulant region 115 defined bythe first meniscus control feature 116 and the third meniscus controlfeature 210 (block 740). The dispensed first encapsulant material 230 iscured (block 750) and a second encapsulant material 240 is dispensedonto the substrate 110 within the third encapsulant region 215 (block760). The dispensed second encapsulant material 240 may be cured (block770).

Continuing with the discussion of FIG. 11, the methods 700 may furtherinclude dispensing a third encapsulant material 250 within the secondencapsulant region 125 (block 780), and curing the third encapsulantmaterial 250 (block 790).

As illustrated above, the dispensed first encapsulant material 230 maydefine a cavity 220 around the LED chip 114, and dispensing the secondencapsulant material 240 may include dispensing the second encapsulantmaterial 240 into the cavity 220 around the LED chip 114 after curingthe first encapsulant material 230. The first encapsulant material 230,the second encapsulant material 240 and/or the third encapsulant 230material may include a wavelength conversion material.

Some methods of the invention include forming a meniscus extensionfeature 300 outside the second encapsulant region 125 surrounding thesecond encapsulant region 125 and defining a encapsulant extension area315 of the upper surface of the substrate 110 (block 800), anddispensing a fourth encapsulant material 330 in the encapsulantextension area 315 after curing the second encapsulant material 140(block 810) and curing the fourth encapsulant material 330 (block 820).

As discussed above in reference to FIGS. 6A-7, the encapsulant extensionarea 315 may have a peripheral shape that is different from a peripheralshape of the second encapsulant region 125. For example, the encapsulantextension area 315 may have a peripheral shape that is oval, circular orgenerally square or rectangular.

The foregoing is illustrative of the present invention and is not to beconstrued as limiting thereof. Although a few exemplary embodiments ofthis invention have been described, those skilled in the art willreadily appreciate that many modifications are possible in the exemplaryembodiments without materially departing from the novel teachings andadvantages of this invention. Accordingly, all such modifications areintended to be included within the scope of this invention as defined inthe claims. Therefore, it is to be understood that the foregoing isillustrative of the present invention and is not to be construed aslimited to the specific embodiments disclosed, and that modifications tothe disclosed embodiments, as well as other embodiments, are intended tobe included within the scope of the appended claims. The invention isdefined by the following claims, with equivalents of the claims to beincluded therein.

1. A submount for mounting an LED, the submount comprising: a substratehaving a planar upper surface; a die attach pad on the upper surface ofthe substrate, the die attach pad configured to receive an LED chip; afirst meniscus control feature on the substrate, the first meniscuscontrol feature comprising a first patterned film on the planar uppersurface of the substrate surrounding the die attach pad, defining afirst encapsulant region of the upper surface of the substrate, andbeing configured to limit the flow of a liquid encapsulant materialacross the substrate, wherein a portion of the planar upper surface ofthe substrate within the first encapsulant region is exposed; and asecond meniscus control feature on the substrate, the second meniscuscontrol feature comprising a second patterned film on the planar uppersurface of the substrate surrounding the first encapsulant region,exposing and defining a second encapsulant region of the upper surfaceof the substrate including an exposed portion of the planar uppersurface of the substrate between the first meniscus control feature andthe second meniscus control feature, and being configured to limit theflow of a liquid encapsulant material across the substrate.
 2. Thesubmount of claim 1, wherein the substrate comprises a printed circuitboard (PCB).
 3. The submount of claim 1, wherein the die attach pad andthe first and second meniscus control features comprise metal traces. 4.The submount of claim 1, wherein the first and/or second meniscuscontrol features comprises a metal film.
 5. The submount of claim 1,wherein the die attach pad and the first and second meniscus controlfeatures comprise the same material.
 6. The submount of claim 5, whereinthe first and/or second meniscus control features comprise a platedmetal film or a polymer feature.
 7. The submount of claim 1, wherein thedie attach pad and the first and second meniscus control features aredirectly on the planar upper surface of the substrate.
 8. The submountof claim 1, further comprising a wirebond pad on the planar uppersurface of the substrate, the wirebond pad disposed within the secondencapsulant region.
 9. The submount of claim 1, wherein the substratecomprises a lower surface opposite the upper surface of the substrate,and wherein the submount further comprises an electrode on the lowersurface of the substrate.
 10. The submount of claim 9, furthercomprising a conductive via extending through the substrate from theelectrode to the die attach pad.
 11. The submount of claim 9, furthercomprising: a wirebond pad on the substrate, the wirebond pad disposedwithin the second encapsulant region; and a conductive via extendingthrough the substrate from the electrode to the wirebond pad.
 12. Thesubmount of claim 1, further comprising an electrode on the uppersurface of the substrate.
 13. The submount of claim 12, wherein theelectrode on the upper surface of the substrate and the first and secondmeniscus control features comprise the same material.
 14. The submountof claim 12, wherein the substrate comprises a lower surface oppositethe upper surface of the substrate, and the submount further comprises alower electrode on the lower surface of the substrate and a conductivevia extending through the substrate from the lower electrode to theelectrode on the upper surface of the substrate.
 15. The submount ofclaim 1, wherein the die attach pad and the first and second meniscuscontrol features comprise metal traces and wherein the die attach padfurther comprises a metal stack on the metal trace.
 16. A submount formounting an LED, the submount comprising: a substrate having a planarupper surface; a patterned film on the planar upper surface of thesubstrate, wherein the patterned film comprises: a portion configured toreceive an LED chip; a first meniscus control feature on the planarupper surface of the substrate defining a first encapsulant region ofthe upper surface of the substrate and configured to limit the flow ofan encapsulant material out of the first encapsulant region; and asecond meniscus control feature on the planar upper surface of thesubstrate defining a second encapsulant region of the upper surface ofthe substrate and configured to limit the flow of an encapsulantmaterial out of the second encapsulant region.
 17. The submount of claim16, wherein the patterned film comprises a conductive trace directly onthe planar upper surface of the substrate.
 18. The submount of claim 16,wherein the patterned film further comprises a wirebond pad disposedwithin the second encapsulant region.
 19. The submount of claim 16,wherein the patterned film further comprises an electrode disposedoutside the second encapsulant region.